This module is automatically opened at the beginning of each compilation.
All components of this module can therefore be referred by their short
name, without prefixing them by Pervasives.

Exceptions

val raise : exn -> 'a

Raise the given exception value

val invalid_arg : string -> 'a

Raise exception Invalid_argument with the given string.

val failwith : string -> 'a

Raise exception Failure with the given string.

exception Exit

The Exit exception is not raised by any library function. It is
provided for use in your programs.

Comparisons

val (=) : 'a -> 'a -> bool

e1 = e2 tests for structural equality of e1 and e2.
Mutable structures (e.g. references and arrays) are equal
if and only if their current contents are structurally equal,
even if the two mutable objects are not the same physical object.
Equality between functional values raises Invalid_argument.
Equality between cyclic data structures may not terminate.

Structural ordering functions. These functions coincide with
the usual orderings over integers, characters, strings
and floating-point numbers, and extend them to a
total ordering over all types.
The ordering is compatible with ( = ). As in the case
of ( = ), mutable structures are compared by contents.
Comparison between functional values raises Invalid_argument.
Comparison between cyclic structures may not terminate.

val compare : 'a -> 'a -> int

compare x y returns 0 if x is equal to y,
a negative integer if x is less than y, and a positive integer
if x is greater than y. The ordering implemented by compare
is compatible with the comparison predicates =, < and >
defined above, with one difference on the treatment of the float value
nan. Namely, the comparison predicates treat nan
as different from any other float value, including itself;
while compare treats nan as equal to itself and less than any
other float value. This treatment of nan ensures that compare
defines a total ordering relation.

compare applied to functional values may raise Invalid_argument.
compare applied to cyclic structures may not terminate.

Return the smaller of the two arguments.
The result is unspecified if one of the arguments contains
the float value nan.

val max : 'a -> 'a -> 'a

Return the greater of the two arguments.
The result is unspecified if one of the arguments contains
the float value nan.

val (==) : 'a -> 'a -> bool

e1 == e2 tests for physical equality of e1 and e2.
On mutable types such as references, arrays, strings, records with
mutable fields and objects with mutable instance variables,
e1 == e2 is true if and only if physical modification of e1
also affects e2.
On non-mutable types, the behavior of ( == ) is
implementation-dependent; however, it is guaranteed that
e1 == e2 implies compare e1 e2 = 0.

Return the absolute value of the argument. Note that this may be
negative if the argument is min_int.

val max_int : int

The greatest representable integer.

val min_int : int

The smallest representable integer.

Bitwise operations

val (land) : int -> int -> int

Bitwise logical and.

val (lor) : int -> int -> int

Bitwise logical or.

val (lxor) : int -> int -> int

Bitwise logical exclusive or.

val lnot : int -> int

Bitwise logical negation.

val (lsl) : int -> int -> int

n lsl m shifts n to the left by m bits.
The result is unspecified if m < 0 or m >= bitsize,
where bitsize is 32 on a 32-bit platform and
64 on a 64-bit platform.

val (lsr) : int -> int -> int

n lsr m shifts n to the right by m bits.
This is a logical shift: zeroes are inserted regardless of
the sign of n.
The result is unspecified if m < 0 or m >= bitsize.

val (asr) : int -> int -> int

n asr m shifts n to the right by m bits.
This is an arithmetic shift: the sign bit of n is replicated.
The result is unspecified if m < 0 or m >= bitsize.

Floating-point arithmetic

OCaml's floating-point numbers follow the
IEEE 754 standard, using double precision (64 bits) numbers.
Floating-point operations never raise an exception on overflow,
underflow, division by zero, etc. Instead, special IEEE numbers
are returned as appropriate, such as infinity for 1.0 /. 0.0,
neg_infinity for -1.0 /. 0.0, and nan (``not a number'')
for 0.0 /. 0.0. These special numbers then propagate through
floating-point computations as expected: for instance,
1.0 /. infinity is 0.0, and any arithmetic operation with nan
as argument returns nan as result.

Arc cosine. The argument must fall within the range [-1.0, 1.0].
Result is in radians and is between 0.0 and pi.

val asin : float -> float

Arc sine. The argument must fall within the range [-1.0, 1.0].
Result is in radians and is between -pi/2 and pi/2.

val atan : float -> float

Arc tangent.
Result is in radians and is between -pi/2 and pi/2.

val atan2 : float -> float -> float

atan2 y x returns the arc tangent of y /. x. The signs of x
and y are used to determine the quadrant of the result.
Result is in radians and is between -pi and pi.

val hypot : float -> float -> float

hypot x y returns sqrt(x *. x + y *. y), that is, the length
of the hypotenuse of a right-angled triangle with sides of length
x and y, or, equivalently, the distance of the point (x,y)
to origin.Since 4.00.0

val cosh : float -> float

Hyperbolic cosine. Argument is in radians.

val sinh : float -> float

Hyperbolic sine. Argument is in radians.

val tanh : float -> float

Hyperbolic tangent. Argument is in radians.

val ceil : float -> float

Round above to an integer value.
ceil f returns the least integer value greater than or equal to f.
The result is returned as a float.

val floor : float -> float

Round below to an integer value.
floor f returns the greatest integer value less than or
equal to f.
The result is returned as a float.

val abs_float : float -> float

abs_float f returns the absolute value of f.

val copysign : float -> float -> float

copysign x y returns a float whose absolute value is that of x
and whose sign is that of y. If x is nan, returns nan.
If y is nan, returns either x or -. x, but it is not
specified which.Since 4.00.0

val mod_float : float -> float -> float

mod_float a b returns the remainder of a with respect to
b. The returned value is a -. n *. b, where n
is the quotient a /. b rounded towards zero to an integer.

val frexp : float -> float * int

frexp f returns the pair of the significant
and the exponent of f. When f is zero, the
significant x and the exponent n of f are equal to
zero. When f is non-zero, they are defined by
f = x *. 2 ** n and 0.5 <= x < 1.0.

Truncate the given floating-point number to an integer.
The result is unspecified if the argument is nan or falls outside the
range of representable integers.

val infinity : float

Positive infinity.

val neg_infinity : float

Negative infinity.

val nan : float

A special floating-point value denoting the result of an
undefined operation such as 0.0 /. 0.0. Stands for
``not a number''. Any floating-point operation with nan as
argument returns nan as result. As for floating-point comparisons,
=, <, <=, > and >= return false and <> returns true
if one or both of their arguments is nan.

Character operations

Return the character with the given ASCII code.
Raise Invalid_argument"char_of_int" if the argument is
outside the range 0--255.

Unit operations

val ignore : 'a -> unit

Discard the value of its argument and return ().
For instance, ignore(f x) discards the result of
the side-effecting function f. It is equivalent to
f x; (), except that the latter may generate a
compiler warning; writing ignore(f x) instead
avoids the warning.

String conversion functions

val string_of_bool : bool -> string

Return the string representation of a boolean. As the returned values
may be shared, the user should not modify them directly.

val bool_of_string : string -> bool

Convert the given string to a boolean.
Raise Invalid_argument"bool_of_string" if the string is not
"true" or "false".

val string_of_int : int -> string

Return the string representation of an integer, in decimal.

val int_of_string : string -> int

Convert the given string to an integer.
The string is read in decimal (by default) or in hexadecimal (if it
begins with 0x or 0X), octal (if it begins with 0o or 0O),
or binary (if it begins with 0b or 0B).
Raise Failure"int_of_string" if the given string is not
a valid representation of an integer, or if the integer represented
exceeds the range of integers representable in type int.

val string_of_float : float -> string

Return the string representation of a floating-point number.

val float_of_string : string -> float

Convert the given string to a float. Raise Failure"float_of_string"
if the given string is not a valid representation of a float.

Print a string, followed by a newline character, on
standard output and flush standard output.

val print_newline : unit -> unit

Print a newline character on standard output, and flush
standard output. This can be used to simulate line
buffering of standard output.

Output functions on standard error

val prerr_char : char -> unit

Print a character on standard error.

val prerr_string : string -> unit

Print a string on standard error.

val prerr_int : int -> unit

Print an integer, in decimal, on standard error.

val prerr_float : float -> unit

Print a floating-point number, in decimal, on standard error.

val prerr_endline : string -> unit

Print a string, followed by a newline character on standard error
and flush standard error.

val prerr_newline : unit -> unit

Print a newline character on standard error, and flush
standard error.

Input functions on standard input

val read_line : unit -> string

Flush standard output, then read characters from standard input
until a newline character is encountered. Return the string of
all characters read, without the newline character at the end.

val read_int : unit -> int

Flush standard output, then read one line from standard input
and convert it to an integer. Raise Failure"int_of_string"
if the line read is not a valid representation of an integer.

val read_float : unit -> float

Flush standard output, then read one line from standard input
and convert it to a floating-point number.
The result is unspecified if the line read is not a valid
representation of a floating-point number.

Open the named file for writing, and return a new output channel
on that file, positionned at the beginning of the file. The
file is truncated to zero length if it already exists. It
is created if it does not already exists.
Raise Sys_error if the file could not be opened.

Same as open_out, but the file is opened in binary mode,
so that no translation takes place during writes. On operating
systems that do not distinguish between text mode and binary
mode, this function behaves like open_out.

open_out_gen mode perm filename opens the named file for writing,
as described above. The extra argument mode
specify the opening mode. The extra argument perm specifies
the file permissions, in case the file must be created.
open_out and open_out_bin are special
cases of this function.

Flush the buffer associated with the given output channel,
performing all pending writes on that channel.
Interactive programs must be careful about flushing standard
output and standard error at the right time.

Write one integer in binary format (4 bytes, big-endian)
on the given output channel.
The given integer is taken modulo 232.
The only reliable way to read it back is through the
input_binary_int function. The format is compatible across
all machines for a given version of OCaml.

Write the representation of a structured value of any type
to a channel. Circularities and sharing inside the value
are detected and preserved. The object can be read back,
by the function input_value. See the description of module
Marshal for more information. output_value is equivalent
to Marshal.to_channel with an empty list of flags.

seek_out chan pos sets the current writing position to pos
for channel chan. This works only for regular files. On
files of other kinds (such as terminals, pipes and sockets),
the behavior is unspecified.

Close the given channel, flushing all buffered write operations.
Output functions raise a Sys_error exception when they are
applied to a closed output channel, except close_out and flush,
which do nothing when applied to an already closed channel.
Note that close_out may raise Sys_error if the operating
system signals an error when flushing or closing.

set_binary_mode_out oc true sets the channel oc to binary
mode: no translations take place during output.
set_binary_mode_out oc false sets the channel oc to text
mode: depending on the operating system, some translations
may take place during output. For instance, under Windows,
end-of-lines will be translated from \n to \r\n.
This function has no effect under operating systems that
do not distinguish between text mode and binary mode.

Same as open_in, but the file is opened in binary mode,
so that no translation takes place during reads. On operating
systems that do not distinguish between text mode and binary
mode, this function behaves like open_in.

open_in_gen mode perm filename opens the named file for reading,
as described above. The extra arguments
mode and perm specify the opening mode and file permissions.
open_in and open_in_bin are special
cases of this function.

Read characters from the given input channel, until a
newline character is encountered. Return the string of
all characters read, without the newline character at the end.
Raise End_of_file if the end of the file is reached
at the beginning of line.

input ic buf pos len reads up to len characters from
the given channel ic, storing them in string buf, starting at
character number pos.
It returns the actual number of characters read, between 0 and
len (inclusive).
A return value of 0 means that the end of file was reached.
A return value between 0 and len exclusive means that
not all requested len characters were read, either because
no more characters were available at that time, or because
the implementation found it convenient to do a partial read;
input must be called again to read the remaining characters,
if desired. (See also really_input for reading
exactly len characters.)
Exception Invalid_argument"input" is raised if pos and len
do not designate a valid substring of buf.

really_input ic buf pos len reads len characters from channel ic,
storing them in string buf, starting at character number pos.
Raise End_of_file if the end of file is reached before len
characters have been read.
Raise Invalid_argument"really_input" if
pos and len do not designate a valid substring of buf.

Read the representation of a structured value, as produced
by output_value, and return the corresponding value.
This function is identical to Marshal.from_channel;
see the description of module Marshal for more information,
in particular concerning the lack of type safety.

Return the size (number of characters) of the regular file
on which the given channel is opened. If the channel is opened
on a file that is not a regular file, the result is meaningless.
The returned size does not take into account the end-of-line
translations that can be performed when reading from a channel
opened in text mode.

Close the given channel. Input functions raise a Sys_error
exception when they are applied to a closed input channel,
except close_in, which does nothing when applied to an already
closed channel. Note that close_in may raise Sys_error if
the operating system signals an error.

set_binary_mode_in ic true sets the channel ic to binary
mode: no translations take place during input.
set_binary_mode_out ic false sets the channel ic to text
mode: depending on the operating system, some translations
may take place during input. For instance, under Windows,
end-of-lines will be translated from \r\n to \n.
This function has no effect under operating systems that
do not distinguish between text mode and binary mode.

Operations on format strings

Format strings are used to read and print data using formatted input
functions in module Scanf and formatted output in modules Printf and
Format.

type('a, 'b, 'c, 'd) format4 = ('a, 'b, 'c, 'c, 'c, 'd) format6

Format strings have a general and highly polymorphic type
('a, 'b, 'c, 'd, 'e, 'f) format6. Type format6 is built in.
The two simplified types, format and format4 below are
included for backward compatibility with earlier releases of OCaml.
'a is the type of the parameters of the format,
'b is the type of the first argument given to
%a and %t printing functions,
'c is the type of the result of the %a and %t functions, and
also the type of the argument transmitted to the first argument
of kprintf-style functions,
'd is the result type for the scanf-style functions,
'e is the type of the receiver function for the scanf-style functions,
'f is the result type for the printf-style function.

f1 ^^ f2 catenates formats f1 and f2. The result is a format
that accepts arguments from f1, then arguments from f2.

Program termination

val exit : int -> 'a

Terminate the process, returning the given status code
to the operating system: usually 0 to indicate no errors,
and a small positive integer to indicate failure.
All open output channels are flushed with flush_all.
An implicit exit 0 is performed each time a program
terminates normally. An implicit exit 2 is performed if the program
terminates early because of an uncaught exception.

val at_exit : (unit -> unit) -> unit

Register the given function to be called at program
termination time. The functions registered with at_exit
will be called when the program executes exit,
or terminates, either normally or because of an uncaught exception.
The functions are called in ``last in, first out'' order:
the function most recently added with at_exit is called first.